Rear end camber...pros and cons?
 

'Splain me. I think I know but some you guys are pretty smart...how much is too much or just right?

Pros:
Contact patch

Cons:
Tire wear
Axle becomes a consumable
Cost

Intended use is a Sunday driver and transpo to an event where I get to help put Meguire's instant detailer on Todd's car....:D

Good talk Russ.... been wondering this same thing myself.

Lay off the sauce Bro :lol:

I was just thinking about this today since my floater housing is about to be built.

I'll be curious to hear what the pro's think but IMO if you are thinking about doing this to your car drive on a track first and see how she handles.

My recent run at T-Hill I couldn't get the rear to slide one bit. I couldn't keep up with the track and spent most my time adjusting tire pressures and alignment. Next time out I'll be spending more time adjusting rear roll center.

Cons: Contact Patch

Why's that?

What do you rear tire do?

Accelerate the car, push mostly, and with camber hopefully keep a line in a corner...

Ok how many beers have you had?

I was thinking the same thing :lol:

I lub you guys...:cheers:

:rofl:

You are going to give up some forward bite by adding camber. Adding camber to the front tires does aid in cornering grip but it can decrease braking if you get greedy. You don't have to worry about laying down the power though. The key is finding the balance between the loss of forward bite and lateral traction gain.

You have more rubber to work with out back and it does help make up for the lack of adjustment. I've slowly found more front grip and that means the rear needs to step up it's game to keep the balance right. That's why I added dual adjustables. I had the front working better than the rear finally. That's a good thing. I don't know yet if I can make the front work better than the rear where a little camber would be worth the reduction in forward bite.

4 and 2/3rds.:lol: It was an accident. :lol: You ever heard of a f'n comma there Albert? ha

Good stuff. For sure 335s push our smaller fronts and balance is key. Speaking w AME Matt today and he loves it. Although he's got 275/295s IIRC, he thinks 3/4 to 1 degree would be perfect.

Just a thought, wouldn't a little more shock/swaybar adjustment on the front help the forward bite?

Hiccup

I agree with the tire stagger. I thought my car felt more neutral running 275's all the way around. All part of the tuning process though. If I cant loosen up the rear with my watts next time out I'm throwing the 275's back on the rear.

As far as sway bars go, your not going to know until you drive it. Definitely recommend adjustables front and rear.

If you are running a 335mm rear tire and 275mm or less on the front, I'd be surprised if you can get your front end working well enough to benefit from the camber. I don't think Matt is making much power and he's got a small stagger.

With that being said, he's a suspension engineer and I'm pretty good at drinking beer and one hell of a race car driver. :lol: :rolleyes:

Agreed Gae. I've got too many knobs to turn in my suspension as it is...:yes:

Agree with that too...:D

You and me both, brother. :lol:

A long time ago, (30 yr?) Herb Adams had a book that said sure it can only help. The cheap and easy method he employed was to saw through the axle tube from the top, stopping before you go all the way through. Let the gap close, and weld back up. High tech is wasn't, but back then nothing was. He claimed the axles lived fine, and ran that way at the Daytone 24 hr race. The issue now is that with 335 / 30 rubber, do you really need to camber the rears? He was running 255/60's.

A lot of people discount nascar as old tech, but they are most like what we are mostly running, ie big HP, front heavy, live axle cars. They also know more about what happens throughout a turn than just about anyone because they spend large amounts of time in steady state cornering. When allowed, they run cambered axles. Is it worth the trouble for us? Not likely. As someone else mentioned, our cars already have rear tires that are proportionally oversized compared to the front. Camber is only going to make a difference when the tire is loaded maximally in a lateral direction. Unless you are running big tracks, with long sweeping turns, and you have used all the available lateral grip, you will probably never see the difference. You also might end giving up forward grip in a straight line.

I decided not to build camber into my floater. I wasn't building a race car, and and it isn't like I'm a race car driver. In my opinion there are so many variables to fine tune between the car and driver that the benefits of rear camber are going to be negligible to me in the long run. All hot rods are temperamental by nature and money pits, and I just wanted one less thing that would have to replace and spend money on more frequently. If you were making something that was purpose built to be fast, and you weren't constrained with our common respective tire sizes, etc, etc. then yeah I would say build a cambered rear axle...

Matt

Thanks for pulling me aside. What you are saying makes complete sense. It's hard enough to keep stuff from breaking as it is.

Thanks! I'd like to think I learned something from building a huge money pit, haha. I just want to add that I'm no authority, I've just learned what works for me based on how much I want to spend, and how useful go fast parts really are to me versus $$$, and my driving skill. It seems everyone who can afford to spend big dollars on a car tends to go for the fanciest parts they can, myself included. At the end of the day we just have to acknowledge that money doesn't buy speed, or maintenance free parts. Just look at Blue Balz, that car is fast, but it probably has more money invested in tuning than some pro touring cars are worth. Any number of expensive parts have been replaced, and not all of them have been broken. Additionally some of them probably won't make a noticeable difference in the car's end performance, except in theory. While I have a different attitude, I definitely respect Cris and Karl for chasing after the tenths and hundredths of seconds.

Matt

Actually experiencing the benefit or lack of.. of parts through trial and error does make you somewhat of an authority. :thumbsup:

Just like Todds comments about staggered tire widths and front vs rear grip if you are speaking from experience it's worth listening to.

I want to build a PT car. To me that means the car will be track oriented but able to drive it to the track. I want it to be usable (bearable or better) on the street. Right now the raunchy old school motor is the one compromise to this plan but it is a necessary :D compromise.

I used to be really good at drinking beer. I think I can still hold my own.

:cheers:

Matt makes a number of very good points. Also the tire stagger issue lessens the urgency - thx Todd- but what may kill it for me is the axles as a wear item. I don't really want to have those as a near term service item. More research needed....:yes:

I like to run my cars with the same size tire on all four corners, and I will say that the difference in rear end tracking with the cambered rear is fantastic.

That said, a full floater rear is not a street friendly piece. Recommended service intervals are 300 miles for drive plate greasing.

I would disagree. If you run a tube seal and grease your bearings then yes you will have periodic maintenance but certainly not every 300 miles. Frankly axle tube seals seem a bit pointless to me for street use. The only floater that needs an axle seal is a circle track application which spends a lot of time turning left. In that application the tube seals keep the gear oil in the center section. But in a street/track floater the tube seal is unnecessary. I'm not running tube seals in my floater and the gear oil lubes the hubs just fine. Granted I only have about 500 miles on the car to date but the floater has been a non-issue and I don't expect it to become one.

I approve this message! :thumbsup: :cheers: